An improved wheelchair for climbing stairs and inclined ramps has been described in U.S. patent application Ser. No. 461,654, filed Jan. 27, 1983, now U.S. Pat. No. 4,564,080. The wheelchair in this disclosure includes a number of features which permit a wheelchair or similar conveyance to change from a first wheel base comprised of ground-engaging wheels to a second wheel base comprised of a pair of endless, flexible track when the wheelchair is to be moved up or down an inclined path. The wheels and tracks are motor-driven and a suitable control is provided to allow for forward and reverse movements of the wheelchair and turning movements of the wheelchair.
It has been found that, with a wheelchair of the type described, it is imperative that the wheelchair not go down a stairway or inclined path with the wheels down or go down a stairway which is too steep in slope even when the tracks are down. Thus, a need exists for improvements in a stair-climbing wheelchair to prevent these problems from occurring. The present invention satisfies this need.